Revert "VM: Handle null-comparisons in the flow graph type propagation"

Revert "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 2cd2ffa9497f08c1c5347511e5c6771e60c0721c.

Reason for revert:

  This seems to have caused crashes on various windows builders
  on service tests. The crashes seem to be slightly flaky.

Committed: https://github.com/dart-lang/sdk/commit/30a942f7287e67d4bcf43f2959428033612b1a70

[kustermann, 2017-03-22 13:06:32]

kustermann@google.com changed reviewers:
+ fschneider@google.com

[kustermann, 2017-03-22 13:06:33]

@Florian: These crashes happened a lot on vm-win-debug-ia32-be and
vm-win-debug-ia32-russian-be. Example failures:

https://uberchromegw.corp.google.com/i/client.dart/builders/vm-win-debug-ia32...

It hits an assertion:

e:\b\build\slave\vm-win-debug-ia32-be\build\sdk\runtime\vm\flow_graph_compiler.h:
129: error: expected: deopt_env != NULL

[kustermann, 2017-03-22 13:07:04]

Description was changed from

==========
Revert "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 2cd2ffa9497f08c1c5347511e5c6771e60c0721c.

Reason for revert:

  This seems to have caused crashes on various windows builders
  on service tests. The crashes seem to be slightly flaky.
==========

to

==========
Revert "VM: Handle null-comparisons in the flow graph type propagation"

This reverts commit 2cd2ffa9497f08c1c5347511e5c6771e60c0721c.

Reason for revert:

  This seems to have caused crashes on various windows builders
  on service tests. The crashes seem to be slightly flaky.

Committed:
https://github.com/dart-lang/sdk/commit/30a942f7287e67d4bcf43f2959428033612b1a70
==========

[kustermann, 2017-03-22 13:07:05]

Committed patchset #1 (id:1) manually as
30a942f7287e67d4bcf43f2959428033612b1a70 (presubmit successful).